The story
One of the Freedoms of the Air, defined under the Chicago Convention in 1944.
Etymology from Wiktionary, CC BY-SA 4.0.
fifth freedom rights
Today it means: The right of an airline of one country to land in a different country, pick up passengers, and carry them on to a third country — e.g. a British airline flying to France, collecting passengers, and taking them to Italy. Full definition →